Catheters, such a chest tubes, are routinely used in patients who have had cardiothoracic surgery or chest trauma to drain blood and other biological matter. Use of chest tubes helps maintain cardiorespiratory/hemodynamic stability by avoiding complications related to accumulation of blood and thrombi (blood clots), air, debris, or other fluids in the pericardial sac and pleural space. However, chest tubes often clog after surgery and their occlusion can lead to life threatening complications such as hemothorax, acute tamponade, and pericardial effusion. This compromises postsurgical hemodynamics, adversely influences surgical outcome, and delays recovery. Chest drainage has recently been reported as an independent potential risk factor and predictor of mortality and is also associated with other adverse outcomes, including longer stays in the intensive care unit or hospital and increased duration on mechanical ventilation. Despite many improvements in intra-/post operative care, chest-tube obstruction remains an important contributor to adverse effects on patients' adequate recovery after surgery. In serious cases, the surgeon brings the patient back into the operating room to remove clots around the heart to prevent pericardial tamponade and thus cardiogenic shock. This scenario suggests that the detriment in outcomes associated with postoperative bleeding may be related to inefficient clearing of blood and retained clots from the chest due to chest-tube clogging.
The management of chest tubes has traditionally consisted of makeshift mechanical methods such as milking and tapping the external portion of the tube to remove clots and maintain patency of the tubing. One of the more controversial methods is chest tube stripping, which can generate transient high negative intrathoracic pressure and can actually be detrimental to areas being drained. Milking of chest tubes may inadvertently push any clots back into the intrathoracic portion that may occlude the tube eyelets. It has also been shown that the degree of clogging cannot always be appreciated by inspecting the tubes prior to removal because the intrathoracic portion of the chest tube may be occluded even when the extrathoracic portion appears clear. This state of uncertainty emphasizes the critical need to address current chest tube clearance strategies or to find ways by which to test chest tube clearance systems as a way to improve outcomes and possibly reduce hospital costs. Barriers to progress in the field are how to prevent clogging and maintain patency for the full length of the tube, especially the intrathoracic portion where the side and end holes collect blood that has been shed within the chest.
Currently, there is no reliable method to prevent chest-tube clogging. A heparin coating allows small amounts of molecular heparin to diffuse into the tube's lumen and also makes the tuber's inner surface slippery (low coefficient of friction), but this diffusion has a very limited time frame to maintain therapeutic efficacy. Another option is electroactive polymers embedded in the tube surface to alternately expand and contract, facilitating tube clearance. To reduce pain, drains that change from a larger diameter when placed within the body (to attain the largest drainage area possible) to a smaller diameter prior to removal have been proposed. Also, a variety of tubes with local anesthetics have been introduced to reduce the patient's discomfort and pain. Most solutions cannot provide a prolonged effect and/or cannot be controlled, safe and reliable at the same time. In addition, all existing solutions are limited in their mechanism of action to the tube's inner surface.
Therefore new and more efficient systems, devices and methods to prevent clot formation on both inner and outer surfaces of chest tubes, catheters, and other medical devices with lumens and to maintain patency of drainage tubes is necessary to reduce clot accumulation within the chest and complications linked to that condition. Further, there is a need for a chest-tube drainage system and method that reliably can be implemented without concern for clogging, not only for heart and lung surgery, but especially for expanding minimally invasive and higher acuity urgent and emergent cases.